Random access

ABSTRACT

An apparatus is configured to transmit at least one first random access request by using a first preamble to a first handover target cell or to a first beam provided by a serving cell. If the first random access request is responded, the apparatus carries out a synchronization to the first handover target cell or to the first beam provided by the serving cell. If the first random access request is not responded, the apparatus transmits at least one second random access request by using at least one second preamble to at least one second handover target cell or to at least one second beam provided by the serving cell. The apparatus stores information on not-responded first or second random access requests or resources not used for random access requests, wherein the information comprises preambles used. The apparatus transmits, after being synchronized, the stored information to either the first handover target cell, the at least one second handover target cell or the serving cell for being used in random access resource allocation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage entry of International ApplicationNo. PCT/FI2018/050334, filed May 7, 2018, entitled “RANDOM ACCESS” whichis hereby incorporated by reference in its entirety.

FIELD

The invention relates to communications.

BACKGROUND

The following description of background art may include insights,discoveries, understandings or disclosures, or associations togetherwith disclosures not known to the relevant art prior to the presentinvention but provided by the invention. Some such contributions of theinvention may be specifically pointed out below, whereas other suchcontributions of the invention will be apparent from their context.

In Long Term Evolution (LTE) systems, handover may be performed by auser device when running out of the coverage of a current serving celland a target cell with good enough quality has been found.

In New Radio (NR), when operating in mm wave frequency band, a cell maybe composed of multiple beams. A user device may be served by a specificbeam in a serving cell. The beam mobility within a cell may be handledat physical and MAC sublayer and may thus be transparent for higherlayers. When beam operations are used, a handover may be triggered atLayer 3 by using cell quality measurements of the source and targetcell. But in fact, the user device may be served by one beam in a sourcecell and after the handover, it may be served by one beam in a targetcell.

BRIEF DESCRIPTION

According to an aspect, there is provided an apparatus comprising: atleast one processor and at least one memory including a computer programcode, the at least one memory and the computer program code configuredto, with the at least one processor, cause the apparatus at least to:transmit at least one first random access request by using a firstpreamble to a first handover target cell or to a first beam provided bya serving cell, if responded, carry out a synchronization to the firsthandover target cell or to the first beam provided by the serving cell,if not responded, transmit at least one second random access request byusing at least one second preamble to at least one second handovertarget cell or to at least one second beam provided by the serving cell;store information on not-responded random access requests and/orresources not used for random access requests, wherein the informationcomprises preambles used, and transmit, after being synchronized, thestored information to the first handover target cell, the at least onesecond handover target cell and/or the serving cell for being used inrandom access resource allocation.

According to an aspect, there is provided an apparatus comprising: atleast one processor and at least one memory including a computer programcode, the at least one memory and the computer program code configuredto, with the at least one processor, cause the apparatus at least to:receive, by an access node, information on not-responded random accessrequests and/or resources not used for random access requests, whereinthe information comprises random access preambles; analyze theinformation for finding out resources used for unsuccessful randomaccess attempts or not used for random access attempts, the resourcesbeing indicated by the random access preambles, and avoid allocating theresources used for unsuccessful random access attempts and/or theresources not used for random access requests for further random accessrequest transmissions.

According to an aspect, there is provided a method comprising:transmitting at least one first random access request by using a firstpreamble to a first handover target cell or to a first beam provided bya serving cell, if responded, carrying out a synchronization to thefirst handover target cell or to the first beam provided by the servingcell, if not responded, transmitting at least one second random accessrequest by using at least one second preamble to at least one secondhandover target cell or to at least one second beam provided by theserving cell; storing information on not-responded random accessrequests and/or resources not used for random access requests, whereinthe information comprises preambles used, and transmitting, after beingsynchronized, the stored information to the first handover target cell,the at least one second handover target cell and/or the serving cell forbeing used in random access resource allocation.

According to an aspect, there is provided a method comprising:receiving, by an access node, information on not-responded random accessrequests and/or resources not used for random access requests, whereinthe information comprises random access preambles; analyzing theinformation for finding out resources used for unsuccessful randomaccess attempts or not used for random access attempts, the resourcesbeing indicated by the random access preambles, and avoiding allocatingthe resources used for unsuccessful random access attempts and/or theresources not used for random access requests for further random accessrequest transmissions. According to an aspect, there is provided anapparatus comprising means for transmitting at least one first randomaccess request by using a first preamble to a first handover target cellor to a first beam provided by a serving cell, means for carrying out,if responded, a synchronization to the first handover target cell or tothe first beam provided by the serving cell, means for transmitting, ifnot responded, at least one second random access request by using atleast one second preamble to at least one second handover target cell orto at least one second beam provided by the serving cell; means forstoring information on not-responded random access requests and/orresources not used for random access requests, wherein the informationcomprises preambles used, and means for transmitting, after beingsynchronized, the stored information to the first handover target cell,the at least one second handover target cell and/or the serving cell forbeing used in random access resource allocation.

According to an aspect, there is provided an apparatus comprising meansfor receiving, by an access node, information on not-responded randomaccess requests and/or resources not used for random access requests,wherein the information comprises random access preambles; means foranalyzing the information for finding out resources used forunsuccessful random access attempts or not used for random accessattempts, the resources being indicated by the random access preambles,and means for avoiding allocating the resources used for unsuccessfulrandom access attempts and/or the resources not used for random accessrequests for further random access request transmissions.

According to an aspect, there is provided a distributed system,comprising: means for receiving, information on not-responded randomaccess requests and/or resources not used for random access requests,wherein the information comprises random access preambles; means foranalyzing the information for finding out resources used forunsuccessful random access attempts, the resources being indicated bythe random access preambles, and means for avoiding allocating theresources used for unsuccessful random access attempts and/or theresources not used for random access requests for further random accessrequest transmissions.

A computer program product for a computer, comprising software codeportions for performing, when said product is run on the computer:transmitting at least one first random access request by using a firstpreamble to a first handover target cell or to a first beam provided bya serving cell, if responded, carrying out a synchronization to thefirst handover target cell or to the first beam provided by the servingcell, if not responded, transmitting at least one second random accessrequest by using at least one second preamble to at least one secondhandover target cell or to at least one second beam provided by theserving cell; storing information on not-responded random accessrequests and/or resources not used for random access requests, whereinthe information comprises preambles used, and transmitting, after beingsynchronized, the stored information to the first handover target cell,the at least one second handover target cell and/or the serving cell forbeing used in random access resource allocation.

A computer program product for a computer, comprising software codeportions for performing, when said product is run on the computer:receiving, by an access node, information on not-responded random accessrequests and/or resources not used for random access requests, whereinthe information comprises random access preambles; analyzing theinformation for finding out resources used for unsuccessful randomaccess attempts or not used for random access attempts, the resourcesbeing indicated by the random access preambles, and avoiding allocatingthe resources used for unsuccessful random access attempts and/or theresources not used for random access requests for further random accessrequest transmissions.

LIST OF DRAWINGS

Some embodiments of the present invention are described below, by way ofexample only, with reference to the accompanying drawings, in which

FIG. 1 illustrates an example of a system;

FIG. 2 is a flow chart;

FIG. 3 is another flow chart;

FIG. 4 is a signaling chart;

FIG. 5 illustrates an example of apparatuses, and

FIG. 6 illustrates another example of apparatuses.

DESCRIPTION OF SOME EMBODIMENTS

In the following, different exemplifying embodiments will be describedusing, as an example of an access architecture to which the embodimentsmay be applied, a radio access architecture based on long term evolutionadvanced (LTE Advanced, LTE-A) or new radio (NR, 5G), withoutrestricting the embodiments to such an architecture, however. It isobvious for a person skilled in the art that the embodiments may also beapplied to other kinds of communications networks having suitable meansby adjusting parameters and procedures appropriately. Some examples ofother options for suitable systems are the universal mobiletelecommunications system (UMTS) radio access network (UTRAN orE-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless localarea network (WLAN or WiFi), worldwide interoperability for microwaveaccess (WiMAX), Bluetooth®, personal communications services (PCS),ZigBee®, wideband code division multiple access (WCDMA), systems usingultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks(MANETs) and Internet Protocol multimedia subsystems (IMS) or anycombination thereof.

FIG. 1 depicts examples of simplified system architectures only showingsome elements and functional entities, all being logical units, whoseimplementation may differ from what is shown. The connections shown inFIG. 1 are logical connections; the actual physical connections may bedifferent. It is apparent to a person skilled in the art that the systemtypically comprises also other functions and structures than those shownin FIG. 1.

The embodiments are not, however, restricted to the system given as anexample but a person skilled in the art may apply the solution to othercommunication systems provided with necessary properties.

The example of FIG. 1 shows a part of an exemplifying radio accessnetwork.

FIG. 1 shows user devices 100 and 102 configured to be in a wirelessconnection on one or more communication channels in a cell with anaccess node (such as (e/g)NodeB) 104 providing the cell. The physicallink from a user device to a (e/g)NodeB is called uplink or reverse linkand the physical link from the (e/g)NodeB to the user device is calleddownlink or forward link. It should be appreciated that (e/g)NodeBs ortheir functionalities may be implemented by using any node, host, serveror access point etc. entity suitable for such a usage.

A communications system typically comprises more than one (e/g)NodeB inwhich case the (e/g)NodeBs may also be configured to communicate withone another over links, wired or wireless, designed for the purpose.These links may be used for signalling purposes. The (e/g)NodeB is acomputing device configured to control the radio resources ofcommunication system it is coupled to. The NodeB may also be referred toas a base station, an access point or any other type of interfacingdevice including a relay station capable of operating in a wirelessenvironment. The (e/g)NodeB includes or is coupled to transceivers. Fromthe transceivers of the (e/g)NodeB, a connection is provided to anantenna unit that establishes bi-directional radio links to userdevices. The antenna unit may comprise a plurality of antennas orantenna elements. The (e/g)NodeB is further connected to core network110 (CN or next generation core NGC). Depending on the system, thecounterpart on the CN side can be a serving gateway (S-GW, routing andforwarding user data packets), packet data network gateway (P-GW), forproviding connectivity of user devices (UEs) to external packet datanetworks, or mobile management entity (MME), etc.

The user device (also called UE, user equipment, user terminal, terminaldevice, etc.) illustrates one type of an apparatus to which resources onthe air interface are allocated and assigned, and thus any featuredescribed herein with a user device may be implemented with acorresponding apparatus, also including a relay node. An example of sucha relay node is a layer 3 relay (self-backhauling relay) towards a basestation.

The user device typically refers to a portable computing device thatincludes wireless mobile communication devices operating with or withouta subscriber identification module (SIM), including, but not limited to,the following types of devices: a mobile station (mobile phone),smartphone, personal digital assistant (PDA), handset, device using awireless modem (alarm or measurement device, etc.), laptop and/or touchscreen computer, tablet, game console, notebook, and multimedia device.It should be appreciated that a user device may also be a nearlyexclusive uplink only device, of which an example is a camera or videocamera loading images or video clips to a network. A user device mayalso be a device having capability to operate in Internet of Things(IoT) network which is a scenario in which objects are provided with theability to transfer data over a network without requiring human-to-humanor human-to-computer interaction. The user device may also utilisecloud. In some applications, a user device may comprise a small portabledevice with radio parts (such as a watch, earphones or eyeglasses) andthe computation is carried out in the cloud. The user device (or in someembodiments a layer 3 relay node) is configured to perform one or moreof user equipment functionalities. The user device may also be called asubscriber unit, mobile station, remote terminal, access terminal, userterminal or user equipment (UE) just to mention but a few names orapparatuses.

Various techniques described herein may also be applied to acyber-physical system (CPS) (a system of collaborating computationalelements controlling physical entities). CPS may enable theimplementation and exploitation of massive amounts of interconnected ICTdevices (sensors, actuators, processors microcontrollers, etc.) embeddedin physical objects at different locations. Mobile cyber physicalsystems, in which the physical system in question has inherent mobility,are a subcategory of cyber-physical systems. Examples of mobile physicalsystems include mobile robotics and electronics transported by humans oranimals.

Additionally, although the apparatuses have been depicted as singleentities, different units, processors and/or memory units (not all shownin FIG. 1) may be implemented.

5G enables using multiple input-multiple output (MIMO) antennas, manymore base stations or nodes than the LTE (a so-called small cellconcept), including macro sites operating in co-operation with smallerstations and employing a variety of radio technologies depending onservice needs, use cases and/or spectrum available. 5G mobilecommunications supports a wide range of use cases and relatedapplications including video streaming, augmented reality, differentways of data sharing and various forms of machine type applications(such as (massive) machine-type communications (mMTC), includingvehicular safety, different sensors and real-time control. 5G isexpected to have multiple radio interfaces, namely below 6 GHz, cmWaveand mmWave, and also being integradable with existing legacy radioaccess technologies, such as the LTE. Integration with the LTE may beimplemented, at least in the early phase, as a system, where macrocoverage is provided by the LTE and 5G radio interface access comes fromsmall cells by aggregation to the LTE. In other words, 5G is planned tosupport both inter-RAT operability (such as LTE-5G) and inter-RIoperability (inter-radio interface operability, such as below 6GHz—cmWave, below 6 GHz—cmWave—mmWave). One of the concepts consideredto be used in 5G networks is network slicing in which multipleindependent and dedicated virtual sub-networks (network instances) maybe created within the same infrastructure to run services that havedifferent requirements on latency, reliability, throughput and mobility.

The current architecture in LTE networks is fully distributed in theradio and fully centralized in the core network. The low latencyapplications and services in 5G require to bring the content close tothe radio which leads to local break out and multi-access edge computing(MEC). 5G enables analytics and knowledge generation to occur at thesource of the data. This approach requires leveraging resources that maynot be continuously connected to a network such as laptops, smartphones,tablets and sensors. MEC provides a distributed computing environmentfor application and service hosting. It also has the ability to storeand process content in close proximity to cellular subscribers forfaster response time. Edge computing covers a wide range of technologiessuch as wireless sensor networks, mobile data acquisition, mobilesignature analysis, cooperative distributed peer-to-peer ad hocnetworking and processing also classifiable as local cloud/fog computingand grid/mesh computing, dew computing, mobile edge computing, cloudlet,distributed data storage and retrieval, autonomic self-healing networks,remote cloud services, augmented and virtual reality, data caching,Internet of Things (massive connectivity and/or latency critical),critical communications (autonomous vehicles, traffic safety, real-timeanalytics, time-critical control, healthcare applications).

The communication system is also able to communicate with othernetworks, such as a public switched telephone network or the Internet112, or utilise services provided by them. The communication network mayalso be able to support the usage of cloud services, for example atleast part of core network operations may be carried out as a cloudservice (this is depicted in FIG. 1 by “cloud” 114). The communicationsystem may also comprise a central control entity, or a like, providingfacilities for networks of different operators to cooperate for examplein spectrum sharing.

Edge cloud may be brought into radio access network (RAN) by utilizingnetwork function virtualization (NVF) and software defined networking(SDN). Using edge cloud may mean access node operations to be carriedout, at least partly, in a server, host or node operationally coupled toa remote radio head or base station comprising radio parts. It is alsopossible that node operations will be distributed among a plurality ofservers, nodes or hosts. Application of cloudRAN architecture enablesRAN real time functions being carried out at the RAN side (in adistributed unit, DU 104) and non-real time functions being carried outin a centralized manner (in a centralized unit, CU 108).

It should also be understood that the distribution of labour betweencore network operations and base station operations may differ from thatof the LTE or even be non-existent. Some other technology advancementsprobably to be used are Big Data and all-IP, which may change the waynetworks are being constructed and managed. 5G (or new radio, NR)networks are being designed to support multiple hierarchies, where MECservers can be placed between the core and the base station or nodeB(gNB). It should be appreciated that MEC can be applied in 4G networksas well.

5G may also utilize satellite communication to enhance or complement thecoverage of 5G service, for example by providing backhauling. Possibleuse cases are providing service continuity for machine-to-machine (M2M)or Internet of Things (IoT) devices or for passengers on board ofvehicles, or ensuring service availability for critical communications,and future railway/maritime/aeronautical communications. Satellitecommunication may utilise geostationary earth orbit (GEO) satellitesystems, but also low earth orbit (LEO) satellite systems, in particularmega-constellations (systems in which hundreds of (nano)satellites aredeployed). Each satellite 106 in the mega-constellation may coverseveral satellite-enabled network entities that create on-ground cells.The on-ground cells may be created through an on-ground relay node 104or by a gNB located on-ground or in a satellite.

It is obvious for a person skilled in the art that the depicted systemis only an example of a part of a radio access system and in practice,the system may comprise a plurality of (e/g)NodeBs, the user device mayhave an access to a plurality of radio cells and the system may comprisealso other apparatuses, such as physical layer relay nodes or othernetwork elements, etc. At least one of the (e/g)NodeBs or may be aHome(e/g)nodeB. Additionally, in a geographical area of a radiocommunication system a plurality of different kinds of radio cells aswell as a plurality of radio cells may be provided. Radio cells may bemacro cells (or umbrella cells) which are large cells, usually having adiameter of up to tens of kilometers, or smaller cells such as micro-,femto- or picocells. The (e/g)NodeBs of FIG. 1 may provide any kind ofthese cells. A cellular radio system may be implemented as a multilayernetwork including several kinds of cells. Typically, in multilayernetworks, one access node provides one kind of a cell or cells, and thusa plurality of (e/g)NodeBs are required to provide such a networkstructure.

For fulfilling the need for improving the deployment and performance ofcommunication systems, the concept of “plug-and-play” (e/g)NodeBs hasbeen introduced. Typically, a network which is able to use“plug-and-play” (e/g)Node Bs, includes, in addition to Home (e/g)NodeBs(H(e/g)nodeBs), a home node B gateway, or HNB-GW (not shown in FIG. 1).A HNB Gateway (HNB-GW), which is typically installed within anoperator's network may aggregate traffic from a large number of HNBsback to a core network.

In the following, embodiments suitable for a random access resourceallocation are disclosed in further detail. Random access procedure isprovided for establishing a radio channel between a radio communicationterminal device, such as a user device and an access node. The firststep in the random access procedure is a user device transmitting arandom access preamble. The main purpose of the preamble is to indicateto a network that a random access attempt exists and to obtain uplinktime synchronization. Prior to transmitting a random access request(preamble), the user device has obtained downlink synchronization as apart of cell-search procedure.

In contention free random access (CFRA), a user device has a dedicated(temporary valid) random access preamble and in contention-based randomaccess, the user device selects a random access preamble from a pool ofpreambles allocated to a cell the user device is trying to access to. Anaccess node may inform random access preamble(s) on a broadcast channel.

A random access request (preamble) is typically transmitted on a randomaccess channel (RACH) which is a common physical channel dedicated tothe random access procedure. Uplink transmissions are generallyinitiated through a RACH. RACH is typically an uplink common channelused for transmitting control information and user data. An access nodemay inform the location and period of RACH time slots and a frequencyband on the broadcast channel.

In Long Term Evolution (LTE) systems, handover is performed by a userdevice when running out of the coverage of a current serving cell and atarget cell with good enough quality has been found.

In New Radio (NR), in higher frequency bands, coverage is provided by aset of narrow beams that form the cell, which will likely impact the waymobility and system access procedures are designed.

The beam mobility within a cell is handled at physical and MAC sublayerand are transparent for higher layers. When beam operations are used, ahandover is triggered at Layer 3 by using cell quality measurements ofthe source and target cell. But in fact, the user device may be servedby one beam of a source cell and after the handover, it may be served byone beam of a target cell.

For supporting user device's mobility in beam-based operation, ahandover target cell may provide dedicated random access (RA) resources(preamble, RACH time slots and/or frequency band/carrier) for multiplebeams or synchronization signal (SS) blocks for a user device's accessto the handover target cell. The user device may send a random accessrequest comprising a random access preamble to more than one of theseresources before getting a random access response (RAR). It should beappreciated, that the random access resources may be provided for a beamfailure recovery (BFR) procedure as well. It should be appreciated thatrandom access resources may also be allocated group-based, for examplein machine-to-machine communications.

When a user device receives a random access response, the target cellonly knows on which random access resource the user device carried outthe successful attempt, but it does not know whether the user devicemade previous attempts or not, neither the resources used in thoseattempts.

Some embodiments provide an option to enable a more efficient resourcereservation for a random access.

It should be appreciated that the coding of software for carrying outthe embodiments shown and described below is well within the scope of aperson of ordinary skill in the art.

One embodiment starts in block 200 of FIG. 2. This embodiment issuitable for being carried out by a user device. Terms “receive” and“transmit” may comprise reception or transmission via a radio path.These terms may also mean preparation of a message to the radio path foran actual transmission or processing a message received from the radiopath, for example, or controlling or causing a transmission orreception, when embodiments are implemented by software.

In block 202, at least one first random access request is transmitted byusing a first preamble to a first handover target cell or to a firstbeam provided by a serving cell.

Transmitting a random access preamble may be triggered by handover or abeam failure recovery.

Random access preamble may be random access radio network identifier(RA-RNTI) or any suitable parameter.

For the purpose of a handover, a user device may send an event basedmeasurement report to an access node controlling the source cell (CUpart of gNB, for example). It may comprise cell quality indicator andmeasurement results and/or, in the case of beam-based measurements, beamidentity of at least one beam in the source and target cells. Thehandover command may comprise a list of dedicated and/or common randomaccess resources corresponding to different beams or cells in the targetcell.

When a user device is not able to communicate anymore with a servingbeam, it may perform a beam failure recovery procedure using resourcesconfigured by network.

The user device may choose the order of cells and/or beams for randomaccess attempts. Typically, the user device selects the strongest cellor beam first, but other criteria may also be used, such as cell load,cell size compared to mobility, quality of service available incells/beams, which operator provides the network, etc. The precisealgorithm or criteria used for the selection is not limiting to theimplementation of embodiments.

It should be appreciated that dedicated RACH configuration allocatesRACH resource(s) together with a respective quality threshold. Whendedicated RACH resources are provided, they are prioritized by a userdevice and the user device shall not switch to contention-based RACHresources as long as the quality threshold of those dedicated resourcesis met.

In NR, random access requests associated with delay sensitive servicesmay be configured to apply a combination of preambles (or preamblesignatures) at a given random access time slot.

Specifically, a higher priority device may transmit a plurality ofpreambles, and even though a collision may occur with the preambletransmitted by a lower priority device, the network is able to detectthe high priority device and grant transmission resources to it. Thus,in some cases, a first preamble may comprise a plurality of preamblestransmitted by using different time slots, for example.

It should be understood that the transmission of the first preamble maybe repeated, usually as timer controlled, if a random access response isnot repeated in a given period of time.

In blocks 204 and 206, if responded, synchronization is carried out tothe first handover target cell or to the first beam provided by theserving cell.

In the case of a handover, the synchronization is carried out to ahandover target cell. However, it should be appreciated that thehandover may also be carried as beam-based, meaning that the handovertarget cell may comprise several beams and that in practice, thehandover is carried out to a certain beam in the handover target cell.

In the case of a beam failure recovery, the user device usually triesfirst a radio access to another beam provided by the current servingcell.

The response may be a random access response, which may comprise uplinkgrant, timing advance and a temporary identity (cell radio networktemporary identity, C-RNTI, for example). The response may also comprisethe responded preamble.

In LTE, synchronization is based on a primary synchronization signal(PSS) and a secondary synchronization signal (SSS). In NR, a broadcastedsynchronization signal is used as well.

However, since in 5G resources are allocated service-based (networkslicing), synchronization requirements may vary.

It should be understood that in the case synchronization and referencesignals (e.g. for neighbor measurements) are beamformed, the fact that auser device may need to detect a beam that may have a narrow coveragewill lead to the need for a direction synchronization procedure inaddition to time and frequency synchronization, either for datatransmission or acquisition of system information.

In blocks 204 and 208, if not responded, at least one second randomaccess request is transmitted by using at least one second preamble toat least one second handover target cell or to at least one second beamprovided by the serving cell.

Again, the user device may choose the order of cells and/or beams forrandom access attempts. Typically, the user device selects the secondstrongest cell or beam as a next choice, but other criteria may also beused, such as cell load, cell size compared to mobility, quality ofservice available in cells/beams, which operator provides the network,etc. The precise algorithm or criteria used for the selection is notlimiting to the implementation of embodiments.

It should be appreciated that dedicated RACH configuration allocatesRACH resource(s) together with a respective quality threshold. Whendedicated RACH resources are provided, they are prioritized by a userdevice and the user device shall not switch to contention-based RACHresources as long as the quality threshold of those dedicated resourcesis met.

In NR, random access requests associated with delay sensitive servicesmay be configured to apply a combination of preambles (or preamblesignatures) at a given random access time slot. Specifically, a higherpriority device may transmit a plurality of preambles, and even though acollision may occur with the preamble transmitted by a lower prioritydevice, the network is able to detect the high priority device and granttransmission resources to it. Thus, in some cases, a second preamble maycomprise a plurality of preambles transmitted by using different timeslots, for example.

It should be understood that the transmission of the at least one secondpreamble may be repeated, usually as timer controlled, if a randomaccess response is not responded in a given period of time.

If the second random access request is not responded, the user devicemay continue the efforts with yet another preamble to yet another cellor beam and the procedure is repeated. The procedure may be repeatedwith as many preambles and to as many cells of beams as provided by aconfiguration or controlled with a counter or timer, for example. Itshould be understood that the cell of beam may also be a so calledrecovery cell or beam with regard to cell search procedure.

The response may be a random access response, which may comprise uplinkgrant, timing advance and a temporary identity (cell radio networktemporary identity, C-RNTI, for example). The response may also comprisethe responded preamble.

In block 210, information on not-responded random access requests and/orresources not used for random access requests is stored, wherein theinformation comprises preambles used.

The information may comprise the number of the preambles, random accessresources used, associated SS-blocks, associated reference signals (suchas channel state information reference signal, CSI-RS), transmissionpowers, transmission times (time slots used), random access radionetwork temporary identifier (RA-RNTI), the number of efforts using acertain preamble, the number of efforts using a certain resource, orderof the non-responded random access requests, information whether therandom access request was part of the contention-based random access orcontention-free random access procedure and/or information on radiochannel measurements. The information may comprise, as an option oradditionally, information on responded random access requests.

The information may be stored in a table. It may also be time stampedfor dropping out too old information.

The information may be cell-specific and/or beam-specific.

In block 212, transmitting, after being synchronized, the storedinformation to the first handover target cell, the at least one secondhandover target cell and/or the serving cell for being used in randomaccess resource allocation.

After the random access response, the procedure continues with settingup a radio connection for data reception and transmission (or forfurther signaling), for example by the user device transmitting a radioresource control connection (RRC) request using resources assigned inthe random access response.

It should be appreciated that the procedure continues with setting up aradio connection for data reception and transmission (or further controlsignaling) also for block 206 synchronization.

Synchronization procedure and procedures carried out after it forachieving a possibility to transmit and receive data (user data orcontrol data) are basically the same in both cases.

The stored information may be transmitted as a part of a RRC connectionrequest or as a part of RRC connection complete message or as adedicated signaling message, for example on a dedicated or commoncontrol channel.

In principle, the user device transmits the information to a next cellis has a radio connection to. The information may be forwarded to targetcells the user device tried to make an access to but failed.

An access node may use the information a user device collects on randomaccess attempts in resource allocation for future random accessprocedures of user devices. The access node may, for example try toavoid allocating the resources used for unsuccessful random accessattempts and/or the resources not used for random access requests and/orthe access node may prefer the resources used for the responded randomaccess requests. The information may thus be used in enhancingefficiency in resource usage.

The embodiment ends in block 214. The embodiment(s) is repeatable inmany ways. Two examples are shown by arrows 216 and 218 in FIG. 2. Itshould be understood that the embodiment(s) may be repeated one or moretimes with a constant or variable pause between separate rounds. Theoption shown by arrow 216 depicts how the transmission of the firstrandom access preamble can be repeated and the option shown by arrow 218depicts how the transmission of the at least one second random accesspreamble can be repeated.

Another embodiment starts in block 300 of FIG. 3. This embodiment issuitable for being carried out by an access node, such as gNB (may beimplemented as a CU or DU or a combination thereof). Terms “receive” and“transmit” may comprise reception or transmission via a radio path.These terms may also mean preparation of a message to the radio path foran actual transmission or processing a message received from the radiopath, for example, or controlling or causing a transmission orreception, when embodiments are implemented by software.

In block 302, information on not-responded random access requests and/orresources not used for random access requests is received. Theinformation comprises random access preambles (or preamble signatures).

The information may comprise the numbers of the preambles, random accessresources used, associated SS-blocks, associated reference signals (suchas channel state information reference signal, CSI-RS), transmissionpowers, transmission times (time slots used), random access radionetwork temporary identifier (RA-RNTI), the number of efforts using acertain preamble, the number of efforts using a certain resource, orderof the non-responded random access requests, information whether therandom access request was part of the contention-based random access orcontention-free random access procedure and/or information on radiochannel measurements.

The information may comprise, as an option or additionally, informationon responded random access requests.

The information may be cell-specific and/or beam-specific.

The stored information may be received as a part of a radio resourcecontrol (RRC) request or as a part of RRC connection setup completemessage or as a dedicated signaling message, for example on a dedicatedor common control channel.

In block 304, the information is analyzed for finding out resources usedfor unsuccessful random access attempts or not used for random accessattempts, the resources being indicated by the random access preambles.

If the information comprises, as an option or additionally, informationon responded random access requests, it may be analyzed for finding outsuccessfully used resources.

In the analysis, the information may also be combined with otherinformation gathered with regard to user devices, such as locationinformation.

The analysis may be carried out in a central unit (CU) of a gNB, forexample. The analysis may also be carried out by an eNB or by usingcloud computing. It is also possible to store data received from morethan one user device and use it for the analysis. Another option is tostore data from a plurality of user devices into cloud and request thedata or a part of it for analysis by an access node. The data may bereceived directly from at least one user device or via another accessnode or via a memory storage located, for example, in a cloud (datadrop).

The analysis may be statistical, for example, number of unsuccessfulattempts per a certain resource, number of successful attempts per acertain resource, counting a success ratio (how many times successful orunsuccessful effort took place in all efforts by using a certainresource), period of time a certain resource has not been used. Theanalysis may be made for a defined period of time, for example forpreventing from using too old data for improved reliability.

In block 306, the resources used for unsuccessful random access attemptsand/or the resources not used for random access requests are avoided inallocating resources for further random access request transmissions.

The resource allocation may be carried out in a central unit (CU) of agNB, for example. The analysis may also be carried out by an eNB or byusing cloud computing (latency requirements are taken into account). Forlatency reasons, the allocation may be carried out in a distributed unit(DU), where the results of the analysis of block 304 may be stored.

In resource allocation, a plurality of options exists: transmissionpower may be raised, a RACH time slot may be chosen among the ones withthe highest success rate and/or frequency band/carrier may be chosenamong the ones with the highest success rate. On the other hand, if acertain frequency band/carrier is not used by any user device for quitea long period of time, it is not allocated. If in analysis it is noticedthat a certain resource frequently leads to unsuccessful attempts in acertain geographical area, such as in a certain beam, it is notallocated for that beam. Other options naturally exists.

It should be understood that the nature of service may also be takeninto consideration, for example, the best resources may be allocated tothe most latency and/or reliability critical services, where quickhandover is needed.

Instead of or in addition to the avoiding allocating (block 308),preferring in the allocating successfully used random access resources.For preferring successful resources, the access node may use informationon the random access resource allocation it carried out combined withinformation received from one or more user devices on unsuccessfulresources and not used resources. Another option is to receiveinformation comprises information on unsuccessful resources, not usedresources and successfully used resources from one or more user devicesdirectly or via another access node.

Instead of or in addition to avoiding allocating and/or preferring inthe allocating certain resources (block 310), the access node mayforward the information and/or result of the analyzing to another accessnode.

Additionally, based on the analysis, at least one quality threshold forat least one dedicated random access resource may be configured based onthe resources used for unsuccessful random access attempts in an effortto help a user device choose a successful resource. The qualitythreshold may be given for a frequency band or carrier based onmeasurement reports received from one or more user device as a part of anormal procedure in radio network operations. The access node may storethe measurement reports for this usage.

The embodiment ends in block 312. The embodiment(s) is repeatable inmany ways. Two examples are shown by arrows 314 and 316 in FIG. 3. Itshould be understood that the embodiment(s) may be repeated one or moretimes with a constant or variable pause between separate rounds. Theoption shown by arrow 314 depicts how the information may be receivedfrom one or more user devices (directly or via another access node orfrom cloud) one or more times for the analysis. The option shown byarrow(s) 316 (316 a, 316 b) depicts how the resource allocation may berepeated based on new analysis. Naturally the analyzing may be repeatedas well.

In the following, some examples of embodiments described above by meansof FIGS. 2 and 3 are clarified by means of example signaling chart ofFIG. 4. The Figure is simplified for the sake of clarity and furtherdetail can be found in FIGS. 2 and 3. In FIG. 4, user device (UE) 402may be UE 100 or 102 and serving access node 400 DU/CU 100 104/108, andhandover target node 404 may be a similar DU/CU combination. The servingaccess node as well as the handover target node may also be DUs orlocated in CUs depending on the implementation. The following is anexample only and it should not be taken as limiting to the embodiments.

In this example, user device 402 transmits a random access preamble toserving access node 400, if the trigger is beam failure recovery and tohandover target node, if the trigger is handover. Then, after beingsynchronized, the user device transmits the information with regard toits random access attempts to either the serving access node or to thehandover target node depending on the case (BFR or handover). The targethandover node may forward the information to the serving access node.Then either the serving access node or the handover target node, orboth, are able to carry out analysis of the information.

The user device may transmit information on random access attempts as apart of a radio resource control (RRC) connection request or as a partof RRC connection complete message or as a dedicated signaling message,for example on a dedicated or common control channel.

FIG. 5 illustrates a simplified block diagram of an apparatus accordingto an embodiment in relation to FIGS. 2 and/or 4.

An embodiment provides an apparatus which may be a user device or anyother suitable apparatus capable to carry out processes described abovein relation to FIGS. 2 and/or 4.

It should be appreciated that the apparatus may include or otherwise bein communication with a control unit, one or more processors or otherentities capable of carrying out operations according to the embodimentsdescribed by means of FIGS. 2 and/or 4. It should be understood thateach block of the flowchart of FIG. 2 and any combination thereof may beimplemented by various means or their combinations, such as hardware,software, firmware, one or more processors and/or (electronic)circuitry. Terms “receive” and “transmit” may comprise reception ortransmission via a radio path. These terms may also mean preparation ofa message to the radio path for an actual transmission or processing amessage received from the radio path, for example, or controlling orcausing a transmission or reception, when embodiments are implemented bysoftware.

As an example of an apparatus according to an embodiment, it is shownapparatus 500, such as a user device, including facilities in controlunit or circuit/circuitry 504 (including one or more processors, forexample) to carry out functions of embodiments according to FIGS. 2and/or 4. The facilities may be software, hardware or combinationsthereof as described in further detail below.

In FIG. 5, block 506 includes parts/units/modules needed for receptionand transmission, usually called a radio front end, RF-parts, radioparts, remote radio head, etc. The parts/units/modules needed forreception and transmission may be comprised in the apparatus or they maybe located outside the apparatus the apparatus being operationallycoupled to them. The apparatus may also include or be coupled to one ormore internal or external memory units.

Another example of apparatus 500 may include at least one processor 504and at least one memory 502 including a computer program code, the atleast one memory and the computer program code configured to, with theat least one processor, cause the apparatus at least to: transmit atleast one first random access request by using a first preamble to afirst handover target cell or to a first beam provided by a servingcell, if responded, carry out a synchronization to the first handovertarget cell or to the first beam provided by the serving cell, if notresponded, transmit at least one second random access request by usingat least one second preamble to at least one second handover target cellor to at least one second beam provided by the serving cell; storeinformation on not-responded random access requests and/or resources notused for random access requests, wherein the information comprisespreambles used, and transmit, after being synchronized, the storedinformation to the first handover target cell, the at least one secondhandover target cell and/or the serving cell for being used in randomaccess resource allocation.

It should be understood that the apparatus may include or be coupled toother units or modules etc., such as radio parts or radio heads, used inor for transmission and/or reception. This is depicted in FIG. 5 asoptional block 506.

Yet another example of an apparatus comprises means (504, 506) fortransmitting at least one first random access request by using a firstpreamble to a first handover target cell or to a first beam provided bya serving cell, means for (504, 506) carrying out, if responded, asynchronization to the first handover target cell or to the first beamprovided by the serving cell, means (504, 506) for transmitting, if notresponded, at least one second random access request by using at leastone second preamble to at least one second handover target cell or to atleast one second beam provided by the serving cell; means (502) forstoring information on not-responded random access requests and/orresources not used for random access requests, wherein the informationcomprises preambles used, and means (502, 506) for transmitting, afterbeing synchronized, the stored information to the first handover targetcell, the at least one second handover target cell and/or the servingcell for being used in random access resource allocation.

It should be understood that the apparatus may include or be coupled toother units or modules etc., such as radio parts or radio heads, used inor for transmission and/or reception. This is depicted in FIG. 5 asoptional block 506. The apparatus may also include or be coupled to acommunications or user interface.

Although the apparatuses have been depicted as one entity in FIG. 5,different modules and memory may be implemented in one or more physicalor logical entities.

FIG. 6 illustrates a simplified block diagram of an apparatus accordingto an embodiment in relation to FIGS. 3 and/or 4.

Another embodiment provides an apparatus which may be a node (networknode, access node), server, host or any other suitable apparatus capableto carry out processes described above in relation to FIGS. 3 and/or 4.The apparatus is suitable for operating as a serving access node.

It should be appreciated that the apparatus may include or otherwise bein communication with a control unit, one or more processors or otherentities capable of carrying out operations according to the embodimentsdescribed by means of FIGS. 3 and/or 4. It should be understood thateach block of the flowchart of FIG. 3 and any combination thereof may beimplemented by various means or their combinations, such as hardware,software, firmware, one or more processors and/or circuitry. Terms“receive” and “transmit” may comprise reception or transmission via aradio path. These terms may also mean preparation of a message to theradio path for an actual transmission or processing a message receivedfrom the radio path, for example, or controlling or causing atransmission or reception, when embodiments are implemented by software.

As an example of an apparatus according to an embodiment, it is shownapparatus 600, such as an access node, including facilities in controlunit or circuit/circuitry 604 (including one or more processors, forexample) to carry out functions of embodiments according to FIGS. 3and/or 4. The facilities may be software, hardware or combinationsthereof as described in further detail below.

In FIG. 6, block 606 includes parts/units/modules needed for receptionand transmission, usually called a radio front end, RF-parts, radioparts, remote radio head, etc. The parts/units/modules needed forreception and transmission may be comprised in the apparatus or they maybe located outside the apparatus the apparatus being operationallycoupled to them. The apparatus may also include or be coupled to one ormore internal or external memory units.

Another example of apparatus 600 may include at least one processor 604and at least one memory 602 including a computer program code, the atleast one memory and the computer program code configured to, with theat least one processor, cause the apparatus at least to: receive, by anaccess node, information on not-responded random access requests and/orresources not used for random access requests, wherein the informationcomprises random access preambles; analyze the information for findingout resources used for unsuccessful random access attempts or not usedfor random access attempts, the resources being indicated by the randomaccess preambles, and avoid allocating the resources used forunsuccessful random access attempts and/or the resources not used forrandom access requests for further random access request transmissions.

It should be understood that the apparatus may include or be coupled toother units or modules etc., such as radio parts or radio heads, used inor for transmission and/or reception. This is depicted in FIG. 6 asoptional block 606.

Yet another example of an apparatus comprises means (604, 606) forreceiving information on not-responded random access requests and/orresources not used for random access requests, wherein the informationcomprises random access preambles; means (602, 604) for analyzing theinformation for finding out resources used for unsuccessful randomaccess attempts or not used for random access attempts, the resourcesbeing indicated by the random access preambles, and means (602, 604) foravoiding allocating the resources used for unsuccessful random accessattempts and/or the resources not used for random access requests forfurther random access request transmissions.

It should be understood that the apparatus may include or be coupled toother units or modules etc., such as radio parts or radio heads, used inor for transmission and/or reception. This is depicted in FIG. 6 asoptional block 606.

Although the apparatuses have been depicted as one entity in FIG. 6,different modules and memory may be implemented in one or more physicalor logical entities.

It should be appreciated that the operations of the apparatus may alsobe carried out by a distributed system comprising a central unit of agNB and a distributed unit of the gNB optionally aided by cloudservices, such as a cloud memory. This option is further explained abovewith regard to FIGS. 1 and 3. The distributed computing system maycomprise: means for receiving information on not-responded random accessrequests and/or resources not used for random access requests, whereinthe information comprises random access preambles; means for analyzingthe information for finding out resources used for unsuccessful randomaccess attempts, the resources being indicated by the random accesspreambles, and means for avoiding allocating the resources used forunsuccessful random access attempts and/or the resources not used forrandom access requests for further random access request transmissions.

An apparatus may in general include at least one processor, controller,unit, module or (electronic) circuitry designed for carrying outfunctions of embodiments operationally coupled to at least one memoryunit (or service) and to typically various interfaces. A circuitry mayrefer to hardware-only circuit implementations, such as implementationsin only analog and/or digital circuitry, combinations of circuits andsoftware (and/or firmware), such as different kind of processors ofportions of them, software and/or circuit components, such as amicroprocessor(s) or a portion of a microprocessor(s). Further, thememory units may include volatile and/or non-volatile memory. The memoryunit may store computer program code and/or operating systems,information, data, content or the like for the processor to performoperations according to embodiments described above in relation to FIGS.2, 3 and/or 4. Each of the memory units may be a random access memory,hard drive, etc. The memory units may be at least partly removableand/or detachably operationally coupled to the apparatus. The memory maybe of any type suitable for the current technical environment and it maybe implemented using any suitable data storage technology, such assemiconductor-based technology, flash memory, magnetic and/or opticalmemory devices. The memory may be fixed or removable.

The apparatus may be an electronic circuit or a system of electroniccircuits performing a particular function in an electronic device with acomputer program code. The electronic circuit may comprise at least oneprocessor and additionally at least one internal or external memory. Itshould be understood that the term circuit/circuitry or electroniccircuit may refer to all of the following: (a) hardware-only circuitimplementations, such as implementations in only analog and/or digitalcircuitry, and (b) combinations of circuits and software (and/orfirmware), such as (as applicable): (i) a combination of processor(s) or(ii) portions of processor(s)/software including digital signalprocessor(s), software, and memory(ies) that work together to cause anapparatus to perform various functions, and (c) circuits, such as amicroprocessor(s) or a portion of a microprocessor(s), that requiresoftware or firmware for operation, even if the software or firmware isnot physically present. This definition of circuit/circuitry applies toall uses of this term in this application.

The apparatus may be, include or be associated with at least onesoftware application, module, unit or entity configured as arithmeticoperation, or as a program (including an added or updated softwareroutine), executed by at least one operation processor. Programs, alsocalled program products or computer programs, including softwareroutines, applets and macros, may be stored in any apparatus-readabledata storage medium and they include program instructions to performparticular tasks. The data storage medium may be a non-transitorymedium. The computer program or computer program product may also bedownloaded to the apparatus. A computer program product may comprise oneor more computer-executable components which, when the program is run,for example by one or more processors possibly also utilizing aninternal or external memory, are configured to carry out any of theembodiments or combinations thereof described above by means of FIGS. 2,3 and/or 4. The one or more computer-executable components may be atleast one software code or portions thereof. Computer programs may becoded by a programming language or a low-level programming language.

Modifications and configurations required for implementing functionalityof an embodiment may be performed as routines, which may be implementedas added or updated software routines, application circuits (ASIC)and/or programmable circuits. Further, software routines may bedownloaded into an apparatus. The apparatus, such as a node device, or acorresponding component, may be configured as a computer or amicroprocessor, such as single-chip computer element, or as a chipset,including at least a memory for providing storage capacity used forarithmetic operation and an operation processor for executing thearithmetic operation.

Embodiments provide computer programs embodied on a distribution medium,comprising program instructions which, when loaded into electronicapparatuses, constitute the apparatuses as explained above. Thedistribution medium may be a non-transitory medium.

Embodiments provide computer programs comprising instructions which,when the program is executed by an apparatus, cause the apparatus tocarry out embodiments described by means of FIG. 2 or 3.

The computer program may be in source code form, object code form, or insome intermediate form, and it may be stored in some sort of carrier,distribution medium, or computer readable medium, which may be anyentity or device capable of carrying the program. Such carriers includea record medium, computer memory, read-only memory, photoelectricaland/or electrical carrier signal, telecommunications signal, andsoftware distribution package, for example. Depending on the processingpower needed, the computer program may be executed in a singleelectronic digital computer or it may be distributed amongst a number ofcomputers. The computer readable medium or computer readable storagemedium may be a non-transitory medium.

The techniques described herein may be implemented by various means. Forexample, these techniques may be implemented in hardware (one or moredevices), firmware (one or more devices), software (one or moremodules), or combinations thereof. For a hardware implementation, theapparatus may be implemented within one or more application specificintegrated circuits (ASICs), digital signal processors (DSPs), digitalsignal processing devices (DSPDs), programmable logic devices (PLDs),field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, digitally enhanced circuits, otherelectronic units designed to perform the functions described herein, ora combination thereof. For firmware or software, the implementation maybe carried out through modules of at least one chip set (e.g.,procedures, functions, and so on) that perform the functions describedherein. The software codes may be stored in a memory unit and executedby processors. The memory unit may be implemented within the processoror externally to the processor. In the latter case it may becommunicatively coupled to the processor via various means, as is knownin the art. Additionally, the components of systems described herein maybe rearranged and/or complimented by additional components in order tofacilitate achieving the various aspects, etc., described with regardthereto, and they are not limited to the precise configurations setforth in the given figures, as will be appreciated by one skilled in theart.

It will be obvious to a person skilled in the art that, as technologyadvances, the inventive concept may be implemented in various ways. Theinvention and its embodiments are not limited to the examples describedabove but may vary within the scope of the claims.

The invention claimed is:
 1. An apparatus comprising: at least oneprocessor and at least one memory including a computer program code, theat least one memory and the computer program code configured to, withthe at least one processor, cause the apparatus at least to: transmit atleast one first random access request by using a first preamble to afirst handover target cell or to a first beam provided by a servingcell, if responded, carry out a synchronization to the first handovertarget cell or to the first beam provided by the serving cell, if notresponded, transmit at least one second random access request by usingat least one second preamble to at least one second handover target cellor to at least one second beam provided by the serving cell; storeinformation on not-responded first or second random access requests orresources not used for first or second random access requests, whereinthe information comprises preambles used, and transmit, after beingsynchronized, the stored information to the first handover target cell,the at least one second handover target cell or the serving cell forbeing used in random access resource allocation.
 2. The apparatus ofclaim 1, wherein the information further comprises at least one of thefollowing: number of the preambles, random access resources used,associated synchronization signal blocks, associated reference signals,transmission powers, transmission times (time slots used), random accessradio network temporary identifier, number of efforts using a certainpreamble, number of efforts using a certain resource, order of thenon-responded random access requests, information whether the randomaccess request was part of the contention-based random access orcontention-free random access procedure and information on radio channelmeasurements.
 3. The apparatus of claim 1, wherein the informationfurther comprises information on responded random access requests. 4.The apparatus of claim 1, wherein the information is cell-specific orbeam-specific.
 5. The apparatus of claim 1, wherein the random accessrequest cause is a handover or a beam failure recovery procedure.
 6. Anapparatus comprising: at least one processor and at least one memoryincluding a computer program code, the at least one memory and thecomputer program code configured to, with the at least one processor,cause the apparatus at least to: receive, by an access node, informationon not-responded random access requests or resources not used for randomaccess requests, wherein the information comprises random accesspreambles; analyze the information for finding out resources used forunsuccessful random access requests or not used for random accessrequests, the resources being indicated by the random access preambles,and avoid allocating the resources used for unsuccessful random accessrequests or the resources not used for random access requests forfurther random access request transmissions.
 7. The apparatus of claim6, wherein the information further comprises at least one of thefollowing: number of the preambles, random access resources used,associated synchronization signal blocks, associated reference signals,transmission powers, transmission times (time slots used), random accessradio network temporary identifier, number of efforts using a certainpreamble, number of efforts using a certain resource, order of thenon-responded random access requests, information whether the randomaccess request was part of the contention-based random access orcontention-free random access procedure and information on radio channelmeasurements.
 8. The apparatus of claim 6, wherein the informationfurther comprises information on responded random access requests, andthe at least one processor and at least one memory including a computerprogram code, the at least one memory and the computer program code arefurther configured to, with the at least one processor, cause theapparatus at least to prefer the resources used for the responded randomaccess requests in allocating resources for the further random accessrequest transmissions.
 9. The apparatus of claim 6, wherein theconfiguration further comprises a random access update releaseprecondition for the least one handover candidate cell for the userdevice stop carrying out the measurements, if the random access updaterelease precondition is fulfilled.
 10. The apparatus of claim 6, furthercomprising causing the apparatus to, instead of or in addition to theavoiding allocating, preferring in the allocating successfully usedrandom access resources.
 11. The apparatus of claim 6, furthercomprising causing the apparatus to, instead of or in addition to theavoiding allocating, forwarding the information or result of theanalyzing to another access node.
 12. The apparatus of claim 6, furthercomprising: causing the apparatus to, instead of or in addition to theavoiding allocating, prefer in the allocating successfully used randomaccess resources and instead of or in addition to the avoidingallocating or the preferring in the allocating successfully used randomaccess resources, forward the information or result of the analyzing toanother access node.
 13. A method comprising: transmitting at least onefirst random access request by using a first preamble to a firsthandover target cell or to a first beam provided by a serving cell, ifresponded, carrying out a synchronization to the first handover targetcell or to the first beam provided by the serving cell, if notresponded, transmitting at least one second random access request byusing at least one second preamble to at least one second handovertarget cell or to at least one second beam provided by the serving cell;storing information on not-responded first or second random accessrequests or resources not used for first or second random accessrequests, wherein the information comprises preambles used, andtransmitting, after being synchronized, the stored information to thefirst handover target cell, the at least one second handover target celland/or or the serving cell for being used in random access resourceallocation.
 14. The method of claim 13, wherein the information furthercomprises at least one of the following: number of the preambles, randomaccess resources used, associated synchronization signal blocks,associated reference signals, transmission powers, transmission times(time slots used), random access radio network temporary identifier,number of efforts using a certain preamble, number of efforts using acertain resource, order of the non-responded random access requests,information whether the random access request was part of thecontention-based random access or contention-free random accessprocedure and information on radio channel measurements.
 15. The methodof claim 13, wherein the information further comprises information onresponded random access requests.
 16. The method of claim 13, whereinthe information is cell-specific or beam-specific.
 17. The method ofclaim 13, wherein the random access request cause is a handover or abeam failure recovery procedure.
 18. A method comprising: receiving, byan access node, information on not-responded random access requests orresources not used for random access requests, wherein the informationcomprises random access preambles; analyzing the information for findingout resources used for unsuccessful random access attempts requests ornot used for random access attempts requests, the resources beingindicated by the random access preambles, and avoiding allocating theresources used for unsuccessful random access attempts requests and/oror the resources not used for random access requests for further randomaccess request transmissions.
 19. The method of claim 18, wherein theinformation further comprises at least one of the following: number ofthe preambles, random access resources used, associated synchronizationsignal blocks, associated reference signals, transmission powers,transmission times (time slots used), random access radio networktemporary identifier, number of efforts using a certain preamble, numberof efforts using a certain resource, order of the non-responded randomaccess requests, information whether the random access request was partof the contention-based random access or contention-free random accessprocedure and information on radio channel measurements.
 20. The methodof claim 18, wherein the information further comprises information onresponded random access requests, further comprising preferring theresources used for the responded random access requests in allocatingresources for the further random access request transmissions.
 21. Themethod of claim 18, wherein the configuration further comprises a randomaccess update release precondition for the least one handover candidatecell for the user device stop carrying out the measurements, if therandom access update release precondition is fulfilled.
 22. The methodof claim 18, further comprising: instead of or in addition to theavoiding allocating, preferring in the allocating successfully usedrandom access resources.
 23. The method of claim 18, further comprising:instead of or in addition to the avoiding allocating, forwarding theinformation or result of the analyzing to another access node.
 24. Themethod of claim 18, further comprising: instead of or in addition to theavoiding allocating, preferring in the allocating successfully usedrandom access resources and instead of or in addition to the avoidingallocating or the preferring in the allocating, forward the informationor result of the analyzing to another access node.